Adaptive Cruise (i.e., speed) Control (ACC) systems operate much like conventional Cruise Control systems, with the added capability of being able to sense in-path vehicles and to slow the ACC equipped vehicle in response. An ACC equipped vehicle thereby allows its operator to automatically control the vehicle speed, as with conventional Cruise Control, without the necessity of having to deactivate and reactivate control whenever slower traffic is encountered.
As is well known in the art, existing ACC methods and systems use a forward looking range sensor such as radar to sense an in-path vehicle (which may also be referred to as a sensed target or primary target). Based on the radar sensor information, such ACC methods and systems then determine the range and relative velocity (or range rate) of the sensed in-path vehicle. Using the range and range rate, the speed of the ACC equipped vehicle is controlled to maintain a selected following interval between the ACC equipped vehicle and the sensed in-path vehicle. The speed of the ACC equipped vehicle is typically controlled by automatic control of the vehicle throttle actuator. In more advanced ACC methods and systems, vehicle speed may also be controlled by automatic control of vehicle brake actuators. Such ACC methods and systems have the ability to apply a moderate degree of braking to the vehicle to achieve further vehicle deceleration (i.e., in addition to vehicle deceleration achieved via throttle control) in response to an in-path vehicle.
Existing ACC methods and systems, however, do not provide any indication to the operator of the ACC equipped vehicle of a vehicle braking event commanded by such ACC methods and systems. Without such an indication, the vehicle operator may be unaware that the ACC system is automatically braking the vehicle.
Thus, in an ACC system, there exists a need for a method and system for indicating a vehicle braking event to an operator of the vehicle. Such a method and system would determine the occurrence of a vehicle braking event commanded by the adaptive speed control system, and activate a vehicle braking indicator in response to the occurrence of such a vehicle baking event, wherein the vehicle braking indicator is perceptible by the vehicle operator. Such a method and system would provide an indication to the operator of the ACC equipped vehicle of a vehicle braking event commanded by the ACC system. In so doing, such a method and system would provide an increased degree of awareness to the operator of the ACC equipped vehicle that a braking force is being automatically applied to the vehicle.